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Old 10-30-2017, 11:55 AM   #1
Mini-Skoolie
 
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Year: 1972
Engine: Cummins NH220
Crown Bus Electrical

Hi!
I have a 1972 35-foot crown and I m trying to add more batteries as my mechanic says I don't have enough cranking amps, which makes starting the bus more difficult than it needs to be and risks frying the starter.

I currently have 2 duralast with 1000 cranking amps each (80 amp hour each), and I am thinking about adding 2 more in parallel. I am pretty sure these buses were designed with much bigger batteries in mind anyway (the battery slots are huge, way bigger than a car battery) but I am still concerned about frying the circuit and would love to not go blind on this.

Would anyone have s wiring diagram and specs for these old crown buses?
Anyone with some experience? Any advice on how to appraach this best?

Thanks!
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Old 11-04-2017, 08:25 AM   #2
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Originally Posted by hanaiapa View Post
Hi!
I have a 1972 35-foot crown and I m trying to add more batteries as my mechanic says I don't have enough cranking amps, which makes starting the bus more difficult than it needs to be and risks frying the starter.

I currently have 2 duralast with 1000 cranking amps each (80 amp hour each), and I am thinking about adding 2 more in parallel. I am pretty sure these buses were designed with much bigger batteries in mind anyway (the battery slots are huge, way bigger than a car battery) but I am still concerned about frying the circuit and would love to not go blind on this.

Would anyone have s wiring diagram and specs for these old crown buses?
Anyone with some experience? Any advice on how to appraach this best?

Thanks!
Most diesel trucks will start on 2000 cca you may have other issues but if ya need it then I recommend 3 Delco 1200 stud post that should be more than enough. Unless you have a walk in door on your engine like those big Waukesha diesels on the oil rigs. I'd have him check the cranking amps on the starter. All the amps in the world won't turn a weak starter. Upsizing the cables can help too. Also most engines should fire and run within about 3 to 5 revolutions. If yours doesn't I'd look into that as well. Dang I need a building to open a bus shop LoL.

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Old 11-04-2017, 08:30 AM   #3
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Originally Posted by golfersmurf57 View Post
Most diesel trucks will start on 2000 cca you may have other issues but if ya need it then I recommend 3 Delco 1200 stud post that should be more than enough. Unless you have a walk in door on your engine like those big Waukesha diesels on the oil rigs. I'd have him check the cranking amps on the starter. All the amps in the world won't turn a weak starter. Upsizing the cables can help too. Also most engines should fire and run within about 3 to 5 revolutions. If yours doesn't I'd look into that as well. Dang I need a building to open a bus shop LoL.

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Both my buses will start just fine on one group 31 battery with like 925 amps. But those Crowns probably need at least 2 or 3 or an 8D or two.
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Old 11-04-2017, 09:48 AM   #4
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Originally Posted by EastCoastCB View Post
Both my buses will start just fine on one group 31 battery with like 925 amps. But those Crowns probably need at least 2 or 3 or an 8D or two.
You live in the tropics.

Anyplace real humans live would likely need two of those batteries in winter
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Old 11-04-2017, 10:49 AM   #5
Mini-Skoolie
 
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Originally Posted by golfersmurf57 View Post
Most diesel trucks will start on 2000 cca you may have other issues but if ya need it then I recommend 3 Delco 1200 stud post that should be more than enough. Unless you have a walk in door on your engine like those big Waukesha diesels on the oil rigs. I'd have him check the cranking amps on the starter. All the amps in the world won't turn a weak starter. Upsizing the cables can help too. Also most engines should fire and run within about 3 to 5 revolutions. If yours doesn't I'd look into that as well. Dang I need a building to open a bus shop LoL.
I actually have 2 x 850 cca not 2x 1000 cca I mispoke.

Do you think I should upgrade before checking anything else?

And yes please do open a shop
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Old 11-13-2017, 05:06 PM   #6
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Like I said, even 1700 would be enough. My 5.9 has 2 of those 8 D series. Was part of the initial cost of the bus. You can check the specs for the starter through the engine mfr. To check starter amps , disable the fuel solenoid. Install a clip on ammeter around the big cable then turn the engine noting the initial draw and the draw once it's turned for a few seconds. Then compare with the specs. A 10 percent increase is about the service limit. But before condemning the starter, slip the belt(s) off and make sure all accessories turn freely. You can also test the draw with out the belts it should be slightly lower in the running amps lock rotor amps won't change much. Hope this helps.

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Old 11-13-2017, 06:02 PM   #7
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Originally Posted by golfersmurf57 View Post
Like I said, even 1700 would be enough. My 5.9 has 2 of those 8 D series. Was part of the initial cost of the bus. You can check the specs for the starter through the engine mfr. To check starter amps , disable the fuel solenoid. Install a clip on ammeter around the big cable then turn the engine noting the initial draw and the draw once it's turned for a few seconds. Then compare with the specs. A 10 percent increase is about the service limit. But before condemning the starter, slip the belt(s) off and make sure all accessories turn freely. You can also test the draw with out the belts it should be slightly lower in the running amps lock rotor amps won't change much. Hope this helps.

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Thanks it helps a lot!
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Old 11-13-2017, 07:38 PM   #8
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Not saying this is the issue or resolution?
In your first post you listed your cranking amps as well as amp hours?
If that came from reading the lable off of the battery you have then you actually have some house batteries and not real cranking batteries.
True group 31 or 8d batteries will only show cold cranking amps (CCA) and CA cranking amps.
If your batteries are showing amp hours then you have some expensive batteries built to run RV power for lighting that are not going to be capable of cold starting a Diesel engine after its sit for awhile.
My bus after it sits for a little while requires me to wiggle the shifter a little bit around in between reverse and drive but I have air brakes.
There is a lot of online support for your 220 because it is still used in a lot of heavy equipment.if all else fails
Look for a heavy equipment mechanic? There not hard to find if you know where to look and offer beer and food to look at what you have no after the earlier you will always get the latter.
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Old 11-13-2017, 09:22 PM   #9
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Crowns usually had two 8D batteries as standard. An 8D doesn't have that much more CA or CCA than a Group 31, but what it has much more of is Reserve Capacity. The heavier the battery is, the more lead it has, and the greater its RC. RC is the battery's ability to provide its cranking amps over time - a higher RC means that you can crank the engine for longer, useful in cold weather when you may need to crank for 15 seconds and then let the compression heat soak into the engine, wait a minute for the starter to cool, then repeat until there's enough heat in the engine to ignite the fuel. With 8Ds you can do this for a long time, with Group 31s for much less time. In warm weather you can start almost any engine in good condition with just one Group 31, but when the temperature drops is when you need that extra RC. The 220 is not a turbo engine, so it has a higher compression ratio than a turbo engine, meaning that it should start slightly easier especially at altitude.

FYI, I start my 6V92 easily with two Group 31s, but if the engine is really cold I can switch my house batteries to the starter to boost power. If you won't have house batteries I suggest you keep with 8Ds for year-round starting ease. You're right that starters die due to low cranking voltage - as the voltage drops the current rises to maintain the same overall power, and current is what heats things. I don't know what starter your 220 has, but my engine uses a 42MT starter that is rated at up to 10.5 HP: that's a LOT of amps potentially flowing though the cables and connections, so they all have to be in top condition all the time. If you want to measure the cranking amps, an 800 amp DC/AC clamp-on meter with peak hold is needed, such as the Extech EX730 (that was also sold by Sears as the Craftsman Professional 73756).

John
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Old 12-08-2017, 08:27 PM   #10
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I popped out $400 for a fluke and added the inductive ammeter accessory. But I'll use it a lot. Also starters should be tested on a non running engine which means you disable the ignition so all it does is turn. Most starters are rated for running amps in their specs. HP is nice but a useless diagnostic spec unless you want to take it off and check it on a dyno. Get the amperage specs and verify by our starter is good then deal with cranking capacity.

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